Thermostat



APPLICATION FILED JUNE 1. 1920.

J. E. 55E. THERMQSTAT.

2 SHEETS SHEET 1.

Patented June 13, 1922.

I; E. GEE.

THERMOSIAT.

APPLICATION FILED JUNE 1, 1920.

Patent ed June 13, 1922.

2 SHEETSSHEET 2.

JAMES EDWIN GEE, 0F, LO NDON, ENG-LAND,

THERIYIOSTAT.

To all whom it may concern,

. Be it known that 1, James EDWIN (JEE, a

subject of the King of England, residing in London, England, have invented certain new and useful Improvements in Thermostats, of

which the following is a specification.

This invention is for improvements in or relating to thermostats oi the type constructconstruction o-fthermostats of this type and the present invention has for its object to provide a" thermostat which will be more sensitive than those hitherto in use, the ob ject being attained by the particular construction and co-operation of the parts described more fully hereinafter.

The use of the term straight? applied herein to the first-named element, is intended to cover a plate which in longitudinal section is oil. straightline form. Also the term arch as applied to the second member is used herein to denote any convenient form of arched or bow-like or angled part, as for instance a memberforming two sides oi a triangle.

According to the present invention a thermostat oi the type described is characterized by the straight member being constituted by a thin flexible sheet of metal and the arched member or members being each constituted- Specification of Letters Patent. Patented J 13 192 1320. Serial No. 385,565,

the arched member in the region of the central portion and to provide the necessary resilience of the arched member to maintain the stra ght and otherwise flexible member substantially taut. ii

According to a modification of the invention each arched member is constructed in the form of a thin flexible and resilient strip to which inflexible stiffening bars are rigidly secured.

A ifurther feature of the invention is that it enables a thermostat of any one of the abovedescribed constructions, to be used in conjunction with an incubator in such a manner that the -straight or non-arched member, that is to say the member with the high coefficient of expansion, is, throughout its length, substantial'ly on the level of the egg-line of the incubator. Conveniently the straight menr ber can be constituted by two sheets of material spaced apart and arranged one on either side of the egg-line and at equal distances away from that line.

' Some specific and preferred forms of the invention will now be described in detail with the aid of the accompanying drawings, in which-- l Figure '1 is an elements;

Figure 2 is a plan of Figure 1;

Figure 3 is a similar view'to Figure lot a modified form of the invention;

l igured is an edge view of a modified form of thermostat; and

Figure 5 isa plan looking from the underside of the thermostat.

edge view of the thermostat Like letters indicate like parts throughout the drawings.

In Figures 1 and 2 the central member of the thermostat comprises a rectangularand comparatively thin sheet of zinc A, the length of which is great in comparison with its width. This member constitutes the base of a triangular construction of which the other sides are formed by archedelements B.

Each of the latter elements is preferably composed of elongated thin strips of steel which are both flexible and resilient. member B is provided with stitteners in the form of bars C also of steel which are in themselves rigid and are secured to the meniber A by nuts and bolts as shown. The bars G are or such dimensions as-to leave the cen tral portions and the extremities of the memhers B free of this added stiffening. Each of the members B, therefore, constitutes two Each comparatively rigid steel members the inner ends of which are spaced apart and are con nected or bridged by means of a springy steel strip and which are connected at their outer extremities to the zinc plate A through the medium of the springy steel strips.

To each end of the member A, and on each face of it, are secured transverse bars D riveted to the plate A. of the bars D are secured the ends of the members B by meansof nuts and bolts E.

The central portions of the members B and their extremities are sufiiciently flexible to allow ready movement of the parts during expansion or contraction.

It is preferred to assemble each member comprising the parts B and C in the form of a fiat plate suiiiciently greaterin length than the zinc plate, so that when it is connected to the latter the ends of the member B meet theplate A at an angle of about 4 or 5 degrees. When the members B are secured to the member A, the springiness of the members. B tends .to draw the member A taut and to retain it so during variation in temperature. The effect of the stitliening plates C is to concentrate the movement of the thermostat in the region oi the rod l Either or both or the members B are connected. in known manner to whatever device the thermostat is required to control. In the form shown a rod F is connected by means of nuts G to the lower member B and passes through orilices in the member Aand in the upper member B respectively for free endwise movement. The upper end of the rod F can then be connected to any desired controlling device. The thermostat is secured to a portion of the incubator-casing, tor example the top wall indicated by the letter X. by means ofa tube H secured at its opposite ends to the middle or apex of the upper member B and to the part Xrespectively. The rod F passes through the member H and through an orifice in the part X, and it will be appreciated therefore that the combined movements of the two members B are added to one another in the movement which is imparted by the rod F to the controlling device.

It will be readily appreciated that with a rise intemperature the zinc plate A expands in length to a greater extent than do the steel arches B. so that thelatter are straightened out or collapsed towards the zinc plate.

With a fall in temperature a reversal of this movement takes place.

In the modification illustrated in Figure 3, the members G, instead of being applied to a single length of springy or flexible material such as B, are connected or spanned as to their adjacent or inner ends by a strip oi: flexible material K suitably connected therewith and their outer ends are similarly provided with flat plates K of flexible ma- To the outer, surfaces Tot the left-hand member C. can pass. free end of the extension M is secured by terial by which member A In Figures 4 and 5 a modified -form of thermostat is shown in which the straight and arched members areconstructed mainly in a similar manner to the form in which they are illustrated in Figure 3. 0f the upper arched member, however, one of the stifiening members C is extended tree of the flexible connector ll and beyond it in a por tion L which extends approximately to the opposite end of the thermostat couple as shown. it the lower arched member both or" the parts C are extended in opposite directions beyond the central connecting strip K to opposite extremities oi the thermostat couple in portions M M In order to permit of a symmetrical construction the extended portion M oi the right-hand member C is enlarged at N and the central part of the enlargement is removed. This affords an orifice through which the extension M. The

they are connected with the means of a strip spring ()to a base-block I mounted on any desired supportand the corresponding end of the extension M connected by means of a looped strip spring; U to a fixed block P The free extremity of the extension L has means Q by which it may be secured to wire or other connector forming part of an operative connection between the thermostat and the device that it is to control.

With the construction described the movement imparted to the member which is controlled by the thermostat is considerably amplified in comparison with that which would be given by the previously described constructions anorduring movement of the parts under the influence of heating or cooling the spring Q, or flexible connector of other preferred construction will yield suliiciently to allow free movement oi the extensions M and M without impeding the operation of the thermostat couple.

W hen using the therl'nostat with an incubator itis preferable that the zinc memher. that is to say that having the greater coeiiicient oi expansion, be on a level with theegg-line so that variations in temperature oi? this zone may be the variations oi: temperature which effect that member. Coir veniently two zinc plates may be employed in place oi the single member A, and these plates can be spaced apart with nistancepieces betweenthem and they can be so disposed that one plate is above and the other plate below at approximately equal distances away from the egg-line; otherwise the construction of the thermostat as a whole may be similar to that described above.

For the purpose of this invention the term eg -line is used to denote a line in any horizontal plane between the limits of the vertical diameter oi the egg. As all the eggs will not be of exactly the same dimensions it will be appreciated that the limiting planes above referred to can only be considered in the light of approximate planes to deline the region within which the eggiine may be said to lie.

i Vhen the thermostat is employed for regulating the temperature 01 a container other than an incubator it is preferred that the member having the greater coefficient of expansion be situated in a Zone in which it is most desirable that temperature variations should be controlled.

Obviously the invention admits of modifications in details of construction. For instance it is not necessary that the particular metals referred to herein should be those employed for the thermostat elements provided that two metals are chosen, as is well understood, having the requisite disparity between their coeiiicients of expansion.

The zinc or like strip should be suiticientl y thin as to be readily affected by the variations of temperature yet strong enough to withstand the stresses to which it is subjected. If difliculty is encountered in ob taining the requisite length with the desired thinness and rigidity, the zinc or straight element such as A may be composed of two or more strips superimposed one above the other with spaces between them for the circulation of the air or other medium in which they are employed. I

The movement of the thermostat may be multiplied by transmission to a rock-shaft or other part which is to receive movement or adjustment from the thermostat.

\Vhat I claim as my invention and desire to secure by Letters Patent is 1. A thermostat of the type described comprising in combination a straight member constituted by at least one thin flexible sheet of metal, and at least one arched member constituted by a springy or resilient length of metal which is stiffened on both sides of its central portion so as to leave that central portion and both ends flexible and resilient, thus constituting a springelement, the said arched spring-element being conneii-ted in compression to the straight member so that it is adapted to exert a tension along the straight member in the direction of its length even when the latter is expanded under the action 0'! heat, and thus to tend to draw the straight member substantially taut notwithstanding its expan sion and contraction b y reason of changes of temperature, substantially as described.

2. A thermostat oi the type described, comprising in combination a straight member constituted by at least one thin flexible sheet of metal, and at least one arched member constituted by thin flexible portions and inflexible bars, so secured thereto that the arched member is flexible and resilient at its two ends and at its central portion, the said arched member being adapted to exert a tension along the straight member in the direction 01 its length to draw the straight member substantially taut notwithstanding its expansion and contraction by reason oi changes of temperature, substantially as described.

3. A thermostat of the type described, comprising in combination a straight member constituted by at least one thin flexible sheet of metal and at least one arched mem ber constituted by two substantially straight and rigid arms, which arms at their highest oints are se Jarated and brid ed b a llexh p l a:

ble and resilient strip secured to them and at their other ends are flexibly and resiliently connected to the straight member, the said arched members being adapted to exert a tension along the straight member in the direction of its length to draw the straight member substantially taut notwith standing its expansion and contraction by means of changes of temperature, substantially as described.

4. A thermostat of the type described, comprising in combination-a straight member constituted by at least one thin flexible sheet of metal, at least one arched 1nember secured at its ends to the straight member and constituted by a single thin flexible and resilient strip to which inflexible stifi'ening bars are secured to leave the two ends and middle portion of the arched member resilient and flexible, the said arched member being adapted to exert a tension along the straight member in the direction of its length to draw the straight member substantially taut notwithstanding its expansion and contractionby reason of changes of temperature, substantially as described.

In testimony whereof I affix my signature.

JAMES EDWIN GEE. 

